The present invention is directed, in general, to video storage and playback and, more specifically, to systems and methods for storing a plurality of video streams on re-writable random-access media and time- and channel-based retrieval thereof.
Ever since the advent of television, the popular and useful programs and their air times have molded people""s schedules. Examples such as the six o"" clock news (during or after the family dinner) and prime-time shows are abundant. As viewer habits change and the choice of programming (channels) grows, people want to adapt television programming to their schedule, rather than the other way around.
Video cassette recorders (VCRs) have enabled people to tape certain programs at the time they are aired and view them later. The recording medium used in these devices is magnetic tape and is therefore inherently sequential and slow in access. The VCR, although extremely successful as a consumer device, has limited flexibility when the number of television channels increases. Also, the consumer has to remember to program the VCR to record the event. Commercially-available VCR+(copyright) technology has somewhat facilitated the process, but still requires tape management, scheduling and remembering when and what to program.
One frequently employed method of viewing television involves rapidly browsing (xe2x80x9csurfingxe2x80x9d) television channels to search for a program of interest, to watch several programs at once, or to skip ubiquitous commercials. Surfing has become even more popular given the advent of cable and satellite television, wherein many dozens of channels are available for viewing at any given time. On currently available single-screen systems, surfing must be done in real time and as time progresses. In other words, a user can watch one channel and record another channel on a VCR, but the user cannot watch a recorded program and simultaneously record another (unless the user is endowed with multiple VCRs). One of the principle restrictions is that the user cannot go back in time on an arbitrary channel without making a conscious effort to record the channel in advance.
Ideally, a user should be able to walk up to his television set and be able to view, on demand and without delay, everything that he missed during some previous period of time (for instance one day), regardless of channel. Therefore, what is needed in the art is a fundamental increase in the flexibility afforded a user in viewing programs aired over multiple channels. Moreover, what is needed in the art is a way of harnessing the power of digital computers to give the user more power in determining what he wants to watch.
To address the above-discussed deficiencies of the prior art, the present invention provides a digital video recorder (DVR) and a method of operating the same. In one embodiment, the DVR includes: (1) a mass data storage unit that concurrently and continuously receives and digitally stores a plurality of channels and (2) a channel viewer, coupled to the mass data storage unit, that retrieves a portion of one of the plurality of channels from the mass data storage unit based on a received command and presents the portion on a video display device.
The present invention therefore introduces the broad concept of capturing multiple channels concurrently to allow a user to choose what to view both temporally and spatially (if a channel is thought of as a spatial dimension). The digital video recorder of the present invention remedies the shortcomings of traditional video recording methods. The DVR does this by combining an essentially limitless (only limited by the cost of the equipment) capability concurrently to record a number of channels on a random-access medium while being able concurrently to play back any of these channels for viewing.
xe2x80x9cContinuouslyxe2x80x9d is defined, for purposes of the present invention, as without interruption over at least a finite period of time. With respect recording of commercial television, xe2x80x9ccontinuouslyxe2x80x9d may connote indiscriminate inclusion of commercials, station identifications and the like. However, it should be understood that xe2x80x9ccontinuouslyxe2x80x9d does not preclude interruption. Certainly, a user may turn the DVR on or off or pause one or more channels. In some embodiments of the present invention, dead air time, commercials, credits or the like may not be recorded. In a more specific embodiment, the decision of what, or what not, to record is the user""s.
A xe2x80x9cchannelxe2x80x9d is defined, for purposes of the present invention, as a stream of video data (and any accompanying audio data). Channels typically correspond one-for-one with satellite, cable television or digital broadcast television channels.
In one embodiment of the present invention, the digital video recorder records the plurality of channels as a matter of course, and without being specifically prompted. This may be thought of as xe2x80x9cautomaticxe2x80x9d recording. At any point in time, the DVR contains video data that covers a window of time (the length of which depends upon memory capacity) for each of the plurality of channels. The user therefore is relieved of the responsibility of starting and stopping recording, allowing the user to view any video recorded during the window of time.
In a related embodiment, the mass data storage unit stores the plurality of channels on a first-in-first-out basis. As the window of time moves forward, the newest video data can overwrite the oldest. Of course, other criteria may govern overwriting. Further, the window of time may vary depending upon the channel being recorded. The user may identify more important channels for which the window is extended or less important channels for which the window is shortened.
In one embodiment of the present invention, the mass data storage unit stores the plurality of channels in separate files based on channel and timeslot identification. In an alternative embodiment, the data storage unit stores the plurality of channels in a combined channel file. In an embodiment to be illustrated and described, specific formats for separate and combined channel files are presented. Those skilled in the art will recognize, however, that the broad scope of the present invention is in no way limited to a particular file-naming or data-structuring scheme for channel files.
In one embodiment of the present invention, the mass data storage unit stores the plurality of channels together with time information to allow the plurality of channels to be synchronized with respect to one another. The time information can synchronize corresponding portions of the plurality of channels that the DVR recorded concurrently. This allows a user to surf synchronized, prerecorded channels in a way that imitates the real-time channel surfing that the prior art constrains the user to do.
In one embodiment of the present invention, the channel viewer comprises a channel guide database containing pointers to locations in the mass data storage unit. The locations may correspond to starting points for individual programs. The channel guide database allows individual programs to be selected efficiently. However, the present invention does not require a channel guide database.
In one embodiment of the present invention, the channel viewer displays a channel guide on the video display device. The channel guide may provide information regarding a content of the plurality of channels. In a more specific embodiment, the channel guide contains links to locations in the mass data storage unit. The links maybe hypertext links, wherein a user can initiate retrieval and presentation of a particular portion of a selected channel simply by clicking on a particular location in the channel guide. Of course, those skilled in the art will readily perceive other ways of employing an electronic channel guide to advantage.
In one embodiment of the present invention, the DVR further includes a pointing device, cooperable with the channel viewer, that allows a user to issue the command. The pointing device, which may be a conventional mouse, allows a user to xe2x80x9cnavigatexe2x80x9d the video display device in an intuitive manner. However, those skilled in the art will understand that the present invention is in no way limited to a particular type of input device.
In one embodiment of the present invention, the channel viewer presents the portion nonlinearly. Sections of the portion may therefore be skipped, repeated, reversed, randomized or presented at a rate that differs from real-time. In an embodiment to be illustrated and described, commercials or other tedious content may be skipped to advantage. This gives rise to viewing concepts, such as xe2x80x9ccatch-up viewingxe2x80x9d as described hereinafter.
In one embodiment of the present invention, the mass data storage unit receives, digitally compresses and digitally stores the plurality of channels. Of course, the present invention does not require compression and is not limited to a particular type of compression.
In one embodiment of the present invention, the mass data storage unit is a redundant array of independent disks (RAID). Those skilled in the art are familiar with the structure and function of RAIDs and their ability to cause otherwise independent disks to cooperate to provide greater speed, reliability, storage capacity or a combination thereof.
In one embodiment of the present invention, the DVR further includes an archive storage unit, coupled to the channel viewer, that stores the portion selected for archiving . The archive storage unit may be a conventional, analog video tape recorder, digital video tape recorder, video disk recorder or other disk (such as commercially available Syqueset(copyright) and Jazz(copyright) disks). In a manner to be set forth below in greater detail, archiving allows the portion to escape overwriting.
In one embodiment of the present invention, the DVR further includes a channel selector, coupled to the mass data storage unit, that allows a user to identify the plurality of channels. Alternatively, the DVR may record all available channels indiscriminately. Selection of channels may be time-based (including, for example, more sports channels over the weekend). The present invention is not limited to a particular manner in which channels are selected for recording.
In one embodiment of the present invention, the mass data storage unit comprises a separate disk volume for each of the plurality of channels. In an alternative embodiment, the mass storage unit comprises a separate physical disk for each of the plurality of channels. Those skilled in the art will understand that the logical or physical structure of the underlying disk storage does not limit the scope of the present invention. However, the underlying structure may be optimized to increase recording or retrieval speed.
In one embodiment of the present invention, the plurality of channels are formatted in a selected one of: (1) NTSC analog TV, (2) PAL/SECAM analog TV, (3) digital TV, (4) analog HDTV and (5) digital HDTV. Those skilled in the art will perceive that the principles of the present invention are applicable to any video (or audio) format.
In one embodiment of the present invention, the DVR selectively moves by one commercial time unit (CTU) within the one of the plurality of channels in response to the received command. The DVR can move forward or backward. In a more specific embodiment, the received command is employable to achieve catch-up viewing. In a manner to be illustrated and described, a user can command the DVR to skip commercials until the time of the portion being viewed merges with real time, at which point the user has xe2x80x9ccaught upxe2x80x9d with the program being viewed.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.